Various treatment for the skin are proposed for delaying, minimizing or even eliminating skin hyperpigmentation (age spots, freckles, blotches, darkening, uneven tone, and the like), wrinkling and other chronical changes typically associated with skin aging or environmental damage to human skin. Such treatment range from application of specialty cosmetics such as packs and masks, oral intake of vitamins, to chemical peeling, laser surgery, photofacial, and others. Generally, it is believed that effective treatment requires more time, physical, and financial commitment. There is a high desire for a treatment which is effective, but is safe and reasonably priced such that the consumer can provide the treatment by himself/herself. PCT application WO 98/51255 teaches an ultrasound application device which has multiple safety features suitable for use by a layperson without the aid of a specialist. Such type of treatment is attractive to the general consumer, as the treatment can be provided at home by the consumer at his/her discretion.
The use of ultrasound to deliver agents transcutaneously, generally termed “sonophoresis” or “phonophoresis”, is known in the art, for example in GB publication 1577551, PCT publication WO 88/00001, PCT publication WO 91/12772, PCT publication WO 94/08655, U.S. Pat. No. 5,267,985, PCT publication WO 97/04832, U.S. Pat. No. 5,445,611, PCT publication WO 97/40679, PCT publication WO 99/51295, U.S. Pat. No. 6,066,123, Japanese patent publication A-11-335271, U.S. publication 2002-55702, and PCT publication WO 00/21605. The depth of penetration into skin of ultrasound is inversely related to the frequency. Ultrasound at lower frequency is believed to provide effect towards deeply into the tissue, thus is effectively used for diagnosis, while higher frequency is believed to provide more effect towards the surface of the skin. PCT publication WO 88/00001 teaches the use of ultrasound at a frequency of no more than about 2.5 MHz for effectively delivering drugs to the circulatory system. To provide an effect to the epidermis of the skin, for example improved penetration of active ingredients that benefit to the epidermis of the skin, ultrasound at higher frequency is effective. Copending Japanese patent application 2002-012143 describes use of higher frequencies for delivery of skin active agents.
For providing a skin care treatment that is safe and effective for the general consumer, further improvement is desired. For example, aqueous gel carriers that have been proposed for use with ultrasound application have been unsatisfactory in effective delivery of skin active agents to the basale epidermidis, and further unsatisfactory in providing good aesthetic/sensory benefits to the skin compared to cosmetic products. In another example, the ultrasound application devices have been unsatisfactory in providing safety features that effectively operate even when applying ultrasound at higher frequencies.
Based on the foregoing, there is a need for a skin care device or method which provides safe and effective skin care treatment benefit via the combined use of skin active agent and ultrasound application. Specifically, there is a need for a composition which, when used in combination with an ultrasound applying apparatus, can effectively deliver the ultrasound to the skin, is stable, while providing smoothness and moisturization to the skin without leaving the skin feel sticky. Meanwhile, there is a need for an ultrasound application apparatus which has a control element for providing the frequency and intensity of ultrasound at a safe and effective level.
None of the existing art provides all of the advantages and benefits of the present invention.